In U.S. Pat. No. 4,098,827, July 4, 1978, Rosenberger, the compound 1-(3-oxo-2,6,6-trimethyl-1-cyclohexen-1-yl)-3-methyl-1,4-methyl-1,4-pentad ien-3-ol which has the formula: ##STR1## has been prepared from a compound of the formula: ##STR2## by first reducing the compound of formula II to produce: ##STR3## and then oxidizing the compound of formula III to produce a compound of formula I. A disadvantage of this process is that the compound of the formula I is produced as an impure mixture. Since the compound of formula I is an intermediate for the known food coloring agent, canthaxanthin, which must be utilized in food in pure form, it is important to produce the intermediate in as pure a form as possible. It has been found that if the compound of formula I is produced from the compound of formula II via the intermediate of formula III, the compound of formula I must be purified by conventional means before it can be used in the further synthesis of commercially acceptable canthaxanthin.